Wilson Newman : I have seen old houses with a summer porch off of the Kitchen This was often where meals on hot days were prepared so as not to heat up the house!
Also Washing Clothes there would bring the finished heavy with rinse water that much closer to the clothesline. Late in the Fall thru to spring the wife would retreat back
into the house for cooking and washing- and the porch would be an alternate place for drying laundry !
THe water in the cistern would be soft water and preferred for washing and laundry, Running out of soft water made more work for the Domestic Goddess
I included a link to an earlier Thread see below :
https://permies.com/t/26825/earth-bag/earthbag-indoor-pool-water-storage
If the well and the cistern were that close they probably were connected to allow well water to be pumped to the cistern- our housewife would not want to run out of water
on wash day- hard water or not !
An answer to your specific question needs more information or pictures You can see however if you have enough slope to use siphoning !
This will reload your question to the top of the posts hopefully someone else can add more info Best Big AL